Digital multimedia products are widely used for entertainment, education and/or other purposes. As used herein, the term “digital multimedia” includes digital audio, digital video and/or digital images which may be embodied in digital multimedia products including, for example, compact discs (CD), digital video discs (DVD), video game products, digital television (DTV) products, memory devices that include digital multimedia files, and digital multimedia files that are distributed over computer networks, such as the World Wide Web, via satellite and/or via cable networks.
With the proliferation of apparatus and methods for producing digital multimedia products, such as digital audio recorders and digital cameras, and multimedia product rendering (using) apparatus, such as digital audio and/or video players, concerns have been raised by owners of copyright and other intellectual property rights in digital multimedia products. These concerns have led to the use and/or proposal of Digital Rights Management (DRM) technologies. These DRM technologies may enable an authorized user of a digital multimedia product to use the product, and may include the ability to copy the product under certain circumstances. DRM technologies also may prohibit unauthorized use by the authorized user, such as sending the digital multimedia product by email and/or publishing the digital multimedia product on the World Wide Web, and may also prohibit use by an unauthorized user.
For example, streaming audio and/or video communications systems and methods, such as marketed by RealNetworks, Inc., Seattle, Wash., can provide real-time playback of audio and/or video data transferred via telephone lines or other communications links. See, for example, U.S. Pat. No. 6,151,634 to Glaser et al. entitled Audio-on-Demand Communication System. DRM may be handled by discarding the data after rendering and/or by allowing the user to register with a DRM server for repeated access.
Another DRM technique is the Secure Digital Music Initiative (SDMI), which allows a limited number of digital copies of a digital multimedia file to be made by integrating a watermark in the file, recording the number of permissible copies, and decrementing this number each time a copy is made. See, for example, Guide to the SDMI Portable Device Specification, Part 1, Version 1.0, Feb. 26, 1999.
Yet another example of DRM technology is the Sony “MagicGate Memory Stick™”, which is a compact integrated circuit recording media equipped with “MagicGate” copyright protection technology. MagicGate is a copyright protection technology that consists of an authentication technology and an encryption technology. Authentication technology ensures that protected content is only transferred between compliant devices and media, and protected content is recorded and transferred in an encrypted format to prevent unauthorized copying or playback. See the press release dated Sep. 22, 1999, entitled Sony Announces “MagicGate Memory Stick™. 
Other DRM technologies may allow a user to store a purchased media product only on a particular device, but may block the user from transferring it outside the device. For example, nearly all current electronic book (e-book) titles sold by trade and academic publishers include some form of security that restricts copying or moving them once they have been downloaded to a personal computer or e-book reading appliance. See, the Frequently Asked Questions (FAQ) at e-books.org, 2002, question entitled “How can I copy or move e-book content from one reading appliance to another?”.